The self-sufficiency rate of edible vegetable oil is less than 32% in China, and can be increased only by expanding farming area. In order to avoid competing with people for grains, and competing with grains for land, vigorously expanding planting in saline-alkali soil to improve the total yield of peanuts is one of the important ways to ensure the safe supply of edible oil in China. As one of the widely cultivated industrial oil crops in the world, peanut is characterized by wide adaptability, drought resistance, barren resistance and symbiosis with nitrogen-fixing rhizobia, contributes to development of water-saving agriculture, improves soil fertility and protects agroecological environment. Improving the area and yield of peanut planted in saline-alkali soil is a task to be completed by peanut researchers.
18 elements are required for peanut growth, where nitrogen, phosphorus, potassium and calcium are most required, and sulfur, boron, molybdenum, zinc, manganese, iron and other trace elements are also indispensable. Through the growth period of peanut, the demand for nutrients is as follows: in the early stage, nitrogen fertilizer is mainly required, and proper amount of nitrogen fertilizer can promote peanut growth and root nodule formation in the seedling stage; in the intermediate stage, calcium fertilizer is mainly required, and is additionally applied to contribute to ideotype formation and promote fruit plumpness; and in the later stage, nitrogen and potassium are mainly required, nitrogen fertilizer is supplemented to prevent fertilizer deficiency in late stage, and potassium fertilizer promotes the transfer of photosynthate to pod. Nitrogen fertilizer is volatile, phosphate fertilizer has weak ability to permeate upward and downward and migrate or diffuse leftward and rightward in soil, potassium fertilizer antagonizes calcium ions, and the root mass of peanut most actively assimilating nutrients is below the fruiting layer. Therefore, peanut fertilizer is most preferably applied to into different layers or released by stages. At present, fertilizers are mainly applied by rationally arranging fertilizer application opportunities, types, quantity and method based on the principle of giving priority to base fertilizer, supplemented by top application, according to the characteristics of peanut's demand for fertilizer and based on the soil fertility. In order to achieve high yield, top application shall be arranged in the middle and later growth stages of peanut, but top application will affect pegging downward and growth. Some fertilizers shall be topdressed under strict conditions, thereby resulting in great difficulties in production. Therefore, top application is labor-consuming and time-consuming.
The prior art provides many solutions for this circumstance, and use of a sustained release and controlled release fertilizer is one widely used solution thereof. For example, CN105367257A discloses a salt-alkali resistant and moistureproof sustained release fertilizer for peanut, including ingredients in the following parts by weight: 30-40 parts of urea, 16-18 parts of ammonium phosphate, 20-30 parts of soybean meal, 15-20 parts of potassium chloride, 12-14 parts of pulverized coal ash, 3-5 parts of polyaspartic acid, 3-5 parts of polysuccinimide, 2-4 parts of mancozeb, 3-5 parts of bactericide, 2-3 parts of brassin, and 1-2 parts of trace element fertilizer. Pulverized coal ash can enable crop straws to become stiff and lodging resistant. Soybean meal is also applied into soil along with a granular fertilizer whilst assimilating moisture in the granular fertilizer and retaining the original granular state thereof, thereby supplementing organic fertilizers into soil. Bactericide and other ingredients reduce drug resistance of crops, have very good control effects, can increase the zinc content in peanut, and promote improvement of the peanut quality. However, the fertilizer fails to improve the salt resistance of peanut, and its nutrient release cannot be synchronous with the peanut demand in growth. In the prior art, there are few controlled release fertilizers integrating salt resistance improvement, etiolated seedling prevention, disease and pest control, growth promotion, pod plumpness promotion, etc.